Biomedical subjects

T Oshika

Publications and source records attributed to T Oshika.

At least 91 records · Page 5Linked to original sources

PubMed1997

[Anterior chamber inflammation after the injection of endothelin-1 into the vitreous and the effect of ETA receptor antagonist].

To assess the receptors which mediate the inflammatory reaction induced by endothelin-1 (ET-1), we investigated the influence of pre-treatment with an ETA receptor antagonist (97-139) on the increase of aqueous protein concentration (APC) after the injection of ET-1 (10(-4), 10(-5)M) into the vitreous cavity of pigmented rabbits. The concentration of prostaglandin E2 (PGE2) and leukotriene B4 (LTB4) in the aqueous humor after the injection of 10(-4)M ET-1 with or without pre-treatment with 97-139 (10(-1), 10(-2), 10(-3)M) was also studied. Pre-treatment with 10(-2)M and 10(-1)M 97-139 completely prevented the APC increase induced by 10(-5)M and 10(-4)M ET-1, respectively. Increases in aqueous PGE2 concentration were observed after the injection of ET-1, which was inhibited by pre-treatment with 97-139. Aqueous LTB4 concentration was not changed significantly by ET-1. These results indicate that the effects of ET-1 on APC are at least partially mediated by the cyclooxygenase pathway of arachidonic acid cascade, and that ETA receptors play an important role in these reactions.

Animals↗

PubMed1996

Effect of folding on the optical quality of soft acrylic intraocular lenses.

PURPOSE: To assess the effect of folding procedures on modulation transfer function (MTF) and resolving power (RP) in soft acrylic intraocular lenses (IOLs). SETTING: Faculty of Engineering, Chiba University, Chiba, Japan. METHODS: Folding procedures and other manipulations were performed on +18.0 diopter soft acrylic lenses (MA60BM, AcrySof, Alcon Surgical). The IOLs were then immersed in the water chamber of a model eye and MTF and RP under veiling glare light measured. The optical surfaces of the IOLs were examined microscopically. RESULTS: After the IOLs had been folded for 30 seconds, MTF recovered 8 and 6 minutes after unfolding in 20 degrees C 37 degrees C balanced salt solution, respectively. Prolonged folding of 10, 20, and 60 minutes did not affect the final MTF, which was measured 30 minutes after unfolding. However, RP deteriorated after the 60 minute folding. Optic damage was observed after the 20 and 60 minute foldings. Neither parameter changed after the IOLs were tightly folded for 30 seconds; however, both deteriorated slightly after the IOLs were tightly folded for 5 minutes, and minor damage was seen on the optics. With fewer than 10 artificial linear cracks in the central 3 mm of the optic, MTF was not affected; with 20 or fewer, RP was not affected. After forceps pressure on the central optic, MTF recovered within 6 minutes. CONCLUSION: The optical quality of soft acrylic IOLs are not easily affected unless extreme nonphysiological manipulations are applied.

Acrylates↗

PubMed1996

Current trends in cataract and refractive surgery in Japan--1995 survey.

A fourth annual survey was carried out by mail in February 1996 to investigate the current trends in cataract and refractive surgery in Japan. A questionnaire was sent to 911 ophthalmologist members of the Japanese Society of Cataract and Refractive Surgery. Data received from 46.7% of the recipients were cross-analyzed and compared with those from the previous surveys.

Adult↗

PubMed1995

Ocular adverse effects of neuropsychiatric agents. Incidence and management.

Neuropsychiatric agents may adversely affect the eye in various ways. The more frequently encountered effects include corneal oedema and pigmentary changes in the lens and cornea which are induced by phenothiazine derivatives; thioridazine-induced retinopathy; tricyclic antidepressant-induced accommodation interference and glaucoma; and lithium carbonate-induced exophthalmos and papilloedema. Several adverse effects, such as corneal oedema, retinopathy and glaucoma, are vision-threatening, and patients often fail to describe their symptoms properly. A more precise understanding of these conditions is essential for prompt diagnosis and appropriate treatment.

Accommodation, Ocular↗

PubMed1995

[Endothelin-1 and intraocular inflammation in pigmented rabbit eyes].

We assessed the role of endothelin-1 (ET-1) in the development of anterior chamber inflammation in pigmented rabbit eyes. After the injection of ET-1 (10(-13), 10(-11), 10(-9) or 10(-7) M) into the anterior chamber, aqueous protein concentration increased significantly in a dose-dependent fashion, with a peak at 1 to 2 hours after treatment, and it returned to the normal level 8 hours after the injection. Pupillary diameter was significantly reduced when 10(-9) M or 10(-7) M ET-1 solution was injected. These effects were blocked by pretreatment with anti-prostaglandin agents, i.e., topical indomethacin or venous diclofenac sodium. In the endotoxin-induced experimental uveitis model, ET-1 concentration in the aqueous humor was significantly higher than that of normal controls as well as the plasma ET-1 level. These results suggest that ET-1 is an important mediator in the ocular inflammatory reactions through the arachidonic acid cascade.

Animals↗

PubMed1995

[Calculation of surgically induced astigmatism].

We compared several mathematical methods for the calculation of surgically induced astigmatism, including Jaffe's horizontal component, Jaffe's vector, Cravy's axis-based cylinder, and Holladay's with-the-wound cylinder. Computer stimulation indicated that Jaffe's vector and Holladay's with-the-wound cylinder methods correctly calculate the surgically induced astigmatism regardless of the direction of wounds. The remaining two methods, however, were found to give erroneous values when the wound is constructed off the x-y axis. Holladay's parameter was least affected by the deviation of the surgical axis. When pre- and postsurgical data of eyes undergoing cataract surgery were analyzed (55 eyes were operated on with a 5.5 mm incision located superiorly, 35 eyes with a 5.5 mm incision located supratemporally, and 40 eyes with a superiorly located 3.2 mm incision), only the Holladay's with-the-wound cylinder method could calculate the actual amount of with-and/or against-the-wound changes.

Aged↗

PubMed1995

[Quantitative evaluation of corneal irregular astigmatism using computed corneal topography].

A new method was developed to quantify corneal irregular astigmatism using computed corneal topography. Refractive powers on a mire ring projected on a toric plane (regular cornea) can be approximated to follow a sine curve. The discrepancy between the approximated sine curve and actual refractive powers was calculated and employed as a parameter of corneal irregular astigmatism. Artificial precision models of a sphere and a toric plane showed similar parameters and the least amount of irregular astigmatism (0.02-0.05D). Consecutive measurements on normal human corneas displayed a reproducible irregular astigmatism range of 0.10-0.25D. Irregular astigatism of the eyes with pterygium was significantly greater than that of normal human controls even from early stages of the disease. Surgery for removal of the pterygium normalized the amount of regular astigmatism regardless of the size of the pterygium, but irregular astigmatism of the eyes with large pterygium (the apex reaching within the central 2 mm cornea) remained at a significantly higher than normal level. It was concluded that the current method enables a quantitative analysis of corneal irregular astigmatism, independent by the amount of regular antigmatism.

Adult↗

PubMed1995

Current trends in cataract and refractive surgery in Japan--1994 survey.

A third annual survey was carried out by mail in January 1995 to investigate the current trends in cataract and refractive surgery in Japan. A questionnaire was sent to 837 ophthalmologist among members of the Japanese Society of Cataract and Refractive Surgery. Data received from 48.5% of the recipients were cross-analyzed and compared with those from the previous surveys.

Adult↗

PubMed1994

Comparative study of intraocular lens implantation through 3.2- and 5.5-mm incisions.

PURPOSE: To prospectively and comprehensively compare the clinical results of two small-incision cataract surgery procedures, silicone intraocular lens (refractive index of 1.46) implantation through a 3.2-mm incision and polymethylmethacrylate intraocular lens implantation through a 5.5-mm incision. METHODS: Two hundred eyes with cataract randomly were assigned to either procedure. Except for incision size, identical surgical methods were used in every case. Data on uncorrected and corrected visual acuity, keratometry, corneal topography, flare-cell measurement, fluorophotometry, specular microscopy, glare disability measurement, and photographic examination of intraocular lens decentration were analyzed up to 6 months after surgery. RESULTS: Eyes in the 3.2-mm incision group displayed significantly better uncorrected and corrected visual acuity in the early postoperative period, lower aqueous flare intensity and cell counts immediately after surgery, less operatively induced astigmatism throughout the study period, and less corneal topographic changes taken 3 months after surgery. No significant between-group differences were noted for other parameters. Complications in the two groups were few and comparable. CONCLUSION: Both procedures of small-incision cataract surgery offered satisfactory clinical results, but 3.2-mm incision cataract surgery allowed significantly earlier recovery of visual function and better preservation of corneal shape.

Aged↗

PubMed1994

[Refractive changes following cataract extraction with intraocular lens implantation].

Refractive changes after six cataract surgery procedures with intraocular lens implantation were assessed; namely, (1) 11 mm incision with running suture closure (n = 25 eyes), (2) 6.5 mm incision with running suture closure (n = 23). (3) 6.5 mm incision with horizontal suture closure (n = 21), (4) 6.5 mm incision without suture closure (n = 40), (5) 5.5 mm incision without suture closure (n = 46), and (6) 3.2 mm incision without suture closure (n = 46). The axis-based keratometric cylinder, absolute value of the induced cylinder vector, and spherical equivalent of the refractive power were analyzed up to 6 months after surgery. Refractive changes did not reach a stable state at 3 months postoperatively for the 11 mm and 6.5 mm running suture closure groups, but they stabilized at 3 months postoperatively for the 6.5 mm horizontal suture and sutureless closure groups, at 1 month postoperatively for the 5.5 mm sutureless closure group, and at 2 weeks postoperatively for the 3.2 mm sutureless closure group. It is concluded that the timing of refractive stabilization differs significantly among procedures, and smaller incisions with wound closure methods which do not exert a vertical force cause fewer postoperative refractive changes.

Aged↗

PubMed1994

[Small incision cataract surgery-silicone intraocular lens vs polymethylmethacrylate intraocular lens].

We compared the postsurgical results of two small incision cataract surgery procedures: silicone intraocular lens implantation through a 3.2 mm incision and polymethylmethacrylate intraocular lens implantation through a 5.5 mm incision. One hundred fifty eyes of 124 patients were randomly assigned to either procedure, and the patients underwent phacoemulsification and intraocular lens implantation without sutures or scleral cautery. Identical surgical techniques were employed in each case except for the size of the incision. Patients in the 3.2 mm incision group showed: (1) better uncorrected and corrected visual acuity in the early postoperative period, (2) lower aqueous flare intensity immediately after surgery, (3) less operatively induced corneal astigmatism throughout the study period up to 3 months after surgery, and (4) less corneal topographic change, i.e., less corneal flattening, 3 months after surgery. There were no significant differences between groups in the corneal endothelial cell loss, blood-aqueous barrier permeability measured by fluorophotometry, or postoperative complications. It was concluded that both procedures offer highly satisfactory clinical results, but that the 3.2 mm incision surgery allows a significantly earlier recovery of visual function and less surgery-induced corneal astigmatism.

Aged↗

PubMed1993

A study on diurnal fluctuation of blood-aqueous barrier permeability to plasma proteins.

The diurnal change of blood-aqueous barrier permeability to protein molecules was investigated in 20 eyes of 10 normal volunteers. Simultaneous determinations of aqueous flow rate and the coefficient of entry into the anterior chamber (k(in)) for plasma protein were performed at different times of the day: (a) 0800 to 1100 hr; (b) 1900 to 2200 hr of the same day; (c) 0800 to 1100 hr of the next day; (d) 1400 to 1700 hr 1 week later; and (e) 0200 to 0500 hr of the following morning. Aqueous flow rate was determined by fluorophotometry and k(in) was calculated for each period from flow rate, plasma protein concentration, anterior chamber volume and aqueous protein concentration measured with a laser flare-cell meter. Calculated values for k(in) did not fluctuate significantly among the periods, and there were no significant changes in anterior chamber volume or plasma protein concentration. Aqueous protein concentration and flow rate showed diurnal fluctuations, the patterns of which inversely corresponded to each other. It was concluded that permeability of the blood-aqueous barrier to protein remains fairly stable over a 24-hr period and the diurnal variation of aqueous protein concentration is mostly attributable to that of aqueous flow rate.

Adult↗

PubMed1993

Current trends in cataract and refractive surgery in Japan--1992 survey.

A survey was carried out by mail in January 1993 to investigate the current trends in cataract and refractive surgery in Japan. A questionnaire was sent to members of the Japanese Intraocular Lens Implant Society, and replies were received from 59.2% prior to the cut-off date of February 15. Results were cross-analyzed and compared with the data from American and British surveys.

Adult↗

PubMed1993

Effects of topical application of UF-021, a novel prostaglandin-related compound, on aqueous humor dynamics in rabbit.

The mechanism underlying the intraocular pressure (IOP) lowering effect of a novel prostaglandin-related compound, (+)-isopropyl Z-7-[(1R,2R,3R,5S)-3,5-dihydroxy-2-(3-oxodecyl)-cyclopentyl]hept-5 -enoate (UF-021), and the influence of this new hypotensive agent on the permeability of the blood-aqueous barrier (BAB) were studied in albino rabbits. A single instillation of 0.06% UF-021 significantly lowered the IOP with a peak reduction of 5.2 mmHg without changing the aqueous flow rate. Uveoscleral outflow and outflow facility to general blood circulation were both increased. The BAB permeability evaluated with fluorescein isothiocyanate-labeled rabbit albumin (FITC-RA) showed approximately sixfold increase after a single instillation of 0.06% UF-021, which suggested a drug-induced compromise of the rabbit BAB.

Administration, Topical↗

PubMed1992

Effect of topical phenylephrine on the permeability of the blood-aqueous barrier in man.

The effects of a single instillation of 5% phenylephrine on aqueous flow and the coefficient of protein entry into the anterior chamber, an index of blood-aqueous barrier permeability, were determined in normal human eyes by measuring fluorescein concentrations with a fluorophotometer and aqueous protein concentrations with a laser flare-cell meter. Both parameters showed a concomitant biphasic change. The coefficient of protein entry showed significant increases of 31 and 66% at 1 and 2 h, and a significant decrease of 18% at 3 h. Aqueous flow showed significant increases of 81 and 125% at 1 and 2 h and a significant decrease of 20% at 4 h. It is suggested that a change in the permeability of the blood-aqueous barrier might be related to changes in aqueous flow after topical phenylephrine.

Administration, Topical↗

PubMed1992

Postsurgical inflammation after phacoemulsification and extracapsular extraction with soft or conventional intraocular lens implantation.

A one-year prospective study was conducted in 120 patients to assess the time course of changes in intraocular inflammation after three cataract surgery procedures: planned extracapsular extraction with poly(methyl methacrylate) (PMMA) intraocular lens (IOL) implantation (11 mm incision group), phacoemulsification with PMMA IOL implantation (7 mm incision group), and phacoemulsification with foldable silicone single-piece IOL implantation (4 mm incision group). Each group was carefully matched for patients' ophthalmologic and systemic backgrounds. Patients with hard nuclei were excluded. The degree of inflammation was evaluated by quantitating aqueous flare intensity and cell count with the laser flare-cell meter. In the early postoperative period, both aqueous flare intensity and cell count were highest in the 11 mm incision group followed, in decreasing order, by the 7 mm and 4 mm incision groups. Significant between-group differences were observed at one, two, and seven postoperative days for flare and one day through one week for cells. Both parameters in each group decreased to a similar level one month after surgery, but flare intensity in all groups remained significantly higher than that of age-matched normal controls up to six months postoperatively.

Aged↗

PubMed1992

[Aqueous protein concentration in diabetics. Report 5. Relationship between aqueous protein concentration and pathological findings of iridial vessels].

The relationship between aqueous protein concentration (APC) and pathological changes in the iridial blood vessels was investigated in 49 eyes of 45 diabetic patients who underwent cataract surgery. APC was measured with a laser flare-cell meter before surgery. The quantification analysis method (type I, multivariate analysis) revealed that the most relevant factor to APC was the existence of nephropathy followed by, in descending order, the degree of retinopathy and changes in iridial vessels as demonstrated by electron microscopy. When data were reanalyzed after exclusion of the iridial vessels were found to be strongly relevant to APC. These results suggest that breakdown of the blood-retinal barrier contributes to the APC increase in eyes with advanced diabetic retinopathy, and that changes in iridial vessels may mainly influence APC in non- and milder-retinopathy groups.

Aged↗

PubMed1992

Effects of pilocarpine and tropicamide on blood-aqueous barrier permeability in man.

The time courses of changes in the effects of topical pilocarpine and tropicamide on the index of the blood-aqueous barrier permeability to plasma protein (Pin) were determined in normal volunteers. Before and after drug instillation in one eye, protein concentration in the anterior chamber (Ca) was determined from aqueous flare intensity with a laser flare-cell meter and from aqueous flow by fluorophotometry. The Pin was calculated from the Ca, plasma protein concentration, and aqueous flow. One percent pilocarpine produced a maximum increase of 21 +/- 10% in the Ca (mean +/- SEM, n = 10), no significant change in the aqueous flow (n = 5), and a maximum increase of 29 +/- 10% in the Pin (n = 10). Three percent pilocarpine produced a maximum increase of 55 +/- 11% in the Ca (n = 8), a maximum increase of 34 +/- 13% in the aqueous flow (n = 5), and a maximum increase of 74 +/- 18% in the Pin (n = 8). Tropicamide (0.4%) produced a maximum decrease of 17 +/- 7% in the Ca (n = 8), a maximum decrease of 15 +/- 11% in the aqueous flow (n = 8), and a maximum decrease of 24 +/- 13% in the Pin (n = 8). The results indicated that pilocarpine increased the blood-aqueous barrier permeability to plasma protein in a dose-dependent manner and that tropicamide reduced it.

Adult↗